Explanation

• Momentum (p) = Mass × Velocity
• A heavier object (like a car) usually has more momentum at the same speed.
• A lighter object (like a bullet) can have more momentum if its velocity is extremely high.

Examples

• Car: Mass = 1000 kg, Speed = 20 m/s → p = 20,000 kg·m/s
• Bullet: Mass = 0.01 kg, Speed = 800 m/s → p = 8 kg·m/s
• Motorcycle: Mass = 200 kg, Speed = 30 m/s → p = 6,000 kg·m/s

Last verified on 15-03-2026

Explanation

• The iris is the colored part of the eye that controls the size of the pupil.
• By adjusting the pupil size, it regulates the amount of light entering the eye, just like a camera diaphragm.
• Pupil dilation occurs in low light, letting in more light.
• Pupil contraction occurs in bright light, protecting the retina from damage.

Last verified on 15-03-2026

Explanation

• According to Newton’s Second Law of Motion: Force (F) = Mass (m) × Acceleration (a)
• It shows that the force applied on an object is proportional to its mass and acceleration.

Additional information:

• Unit of Force – Newton (N)
• 1 N = 1 kg·m/s²

Last verified on 15-03-2026

Explanation

• Steel is an alloy made by combining iron (Fe) with carbon (C).
• Carbon strengthens the iron.
• This making it harder and more durable for construction and tools.

Additional information:

• Brass – Copper + Zinc
• Bronze – Copper + Tin
• Stainless steel – Steel + Chromium + Nickel

Last verified on 15-03-2026

Explanation

• Sound waves first enter the ear through the Ear Canal.
• It is also known as the external auditory meatus.
• From there, they travel to the eardrum, then to the cochlea, and finally to the auditory nerve.

Last verified on 15-03-2026

Explanation

• Transmission is the process where light passes through a material without being absorbed or reflected.
• The light may pass completely unchanged if the material is transparent.

Additional information:

• Reflection – Light bounces back from a surface
• Absorption – Light is taken in by a material and converted to heat
• Refraction – Light bends while passing from one medium to another (like air to water)

Last verified on 15-03-2026

Explanation

Gears can:

• Change speed: Gears can increase or decrease
• Change direction: Gears can change the direction of rotation
• Change force: Gears can increase or decrease the force

However, gears cannot change the fulcrum, which is the pivot point or axis of rotation.

Last verified on 15-03-2026

Explanation

• Fuel stores energy in the form of chemical bonds.
• When fuel burns in the engine, this chemical energy is converted into mechanical energy to move the car.
• Gasoline, diesel, and natural gas are common fuels storing chemical energy.
• The process of burning fuel to release energy is called combustion.

Last verified on 15-03-2026

Explanation

• Limiting factors are environmental conditions that restrict the growth, abundance, or distribution of organisms.
• They determine which species can survive and how many individuals of each species can exist in an ecosystem.
• Limiting factors can be abiotic (non-living) like sunlight, water, or temperature.
• They can also be biotic (living) like competition, predation, or disease.

Last verified on 15-03-2026

Explanation

• During swallowing, the epiglottis (a flap of cartilage) folds down.
• It closes the opening of the trachea (windpipe) so that food enters the esophagus instead of the airway.
• This protective mechanism prevents choking and food entering the lungs.

Last verified on 15-03-2026